Mary Willa "Mamie" Gummer (born August 3, 1983) is an American actress. She starred in the title role of The CW series Emily Owens, M.D. (2012–2013), and played the recurring role of Nancy Crozier on The Good Wife (2010–2015) and its spin-off, The Good Fight (2018). She has also appeared in the films Evening (2007), Side Effects (2013), Cake (2014), and Ricki and the Flash (2015). Gummer was nominated for the 2016 Drama Desk Award for Outstanding Actress in a Play for the original production of Ugly Lies the Bone. She is the daughter of Don Gummer and Meryl Streep.

Early life and education
Gummer was born in New York City and is the eldest daughter of actress Meryl Streep and sculptor Don Gummer. She grew up in Salisbury, Connecticut, and also spent five years in Los Angeles with her older brother, Henry Wolfe Gummer, and younger sisters, actors Grace Gummer and Louisa Jacobson.

Gummer attended Miss Porter's School, and graduated from the Kent School in Kent, Connecticut, before continuing her studies in theater and communications at Northwestern University, graduating in 2005.